Turbomachines often comprise rotor discs, each configured with a generally radially outer rim to which are connected a row of circumferentially-disposed blades. Rotor discs are designed to withstand the centrifugal loads developed by the blades as the rotor discs rotate at very high speeds about a central axis and also other loads resulting from forces acting on the blades during operation of the turbomachines. The strength of rotor discs is generally calculated so as to be maximized while their weight is minimized. The rotor discs are designed to withstand the various loads during their entire planned service life.
The balancing of rotor discs must be done before putting them into service and also after a maintenance operation. A balancing operation is generally carried out with the blades mounted on a rotor disc, the rotor disc and the blades forming a rotor disc assembly. Various balancing techniques exist. Some involve a repositioning of the blades around the rotor discs. Others involve adding balancing weights to the rotor disc or removing material from the rotor discs, for example by machining holes therein. However, adding or removing weight on rotor discs can locally increase internal stresses during rotation, especially when high strength alloys developed for high speed rotor discs are used. These alloys have a lower damage tolerance compared to other materials and can be prone to crack propagation, for instance around holes that may be provided for attaching balancing weights or in areas where material is removed for balancing. Room for improvements thus exists.